A vehicle air bag system functions to protect a vehicle occupant from injury during a crash or collision. The principal components of a vehicle air bag system are an air bag and an inflator. The air bag is stored in a deflated condition at a storage location in the vehicle dashboard or steering wheel. At the onset of a collision, the inflator rapidly generates a large quantity of gas. The gas is directed into the air bag to deploy the air bag into a position in front of a vehicle occupant, and simultaneously to inflate the air bag. When inflated, the air bag restrains the vehicle occupant against impact with a relatively rigid part of the vehicle.
In many known air bag systems, aspirated air, i.e. ambient air drawn from outside the inflator, is used in the inflation process. Specifically, gas generated or released by the inflator induces a flow of ambient air from outside the inflator. The ambient air combines with the gas from the inflator to form an inflation fluid. The inflation fluid is directed into the air bag to deploy and to inflate the air bag.
An example of an aspiration air bag system is disclosed in U.S. Pat. No. 3,632,133 to Hass. The Hass patent discloses a passenger side air bag system comprising a receptacle built into the vehicle dashboard and a folded air bag. The system also comprises a nozzle-shaped aspirator member located in the receptacle, and a cover which closes the receptacle and forms part of the dashboard. The nozzle-shaped member is in fluid communication with the passenger compartment, through passageways in the dashboard. An inflator is connected to, and disposed within, the nozzle-shaped member. The inflator has a cylindrical housing and a gas discharge mechanism formed at one end of the cylindrical housing. The gas discharge mechanism communicates with the throat of the nozzle-shaped member. When the inflator is actuated, gas from the inflator is directed through the gas discharge mechanism of the inflator and into the throat of the nozzle-shaped member. Air is drawn into the nozzle-shaped member and combines with the gas from the inflator to form an inflation fluid which is directed into the air bag, to deploy and to inflate the air bag.
The aspiration air bag system shown in the Hass patent is installed in a vehicle by installing the various components of the system, in stages, into the vehicle dashboard. However, it is now desirable to have air bag modules which can be assembled outside the vehicle and then be loaded as complete units into vehicles. Such air bag modules can be assembled, and installed in a vehicle, by mass production techniques. Also, such air bag modules can be efficiently replaced, after their air bags have been deployed.
One well known air bag module construction comprises a metal reaction can in which an air bag and an inflator are loaded, and a cover which closes the can to complete the module. The reaction can is adapted to be coupled to a structural part of a vehicle, to couple the module to the vehicle. Another known module construction is illustrated in U.S. Pat. No. 4,915,410. A reaction plate and a cup-shaped cover are coupled together to define a cavity for an inflator and an air bag. The air bag and the inflator are coupled to the reaction plate. The reaction plate is adapted to be connected to a structural part of the vehicle to couple the module to the vehicle. In either of the foregoing module constructions, the reaction device, i.e. either the reaction can or the reaction plate, is the structural element to which the air bag and the inflator are coupled and which is coupled to the vehicle to incorporate the module into the vehicle.